The field of rapid thermal processing (RTP) has dealt mainly with the uniformity of heating of the semiconductor wafers treated in the RTP systems. RTP systems generally have a chamber with at least one wall transparent to radiation from sources of radiation such as lamps. The object to be processed is placed in the chamber and irradiated with radiation from the radiation source so that the object is heated. The chamber with the transparent wall is not strictly necessary in the system, provided that the system controls the atmosphere in which the object is placed during processing. The lamps could then be placed in proximity to the object without the intervening window. Much progress has been made in using batteries of lamps with individual control of each lamp to increase uniformity of the illuminating radiation. The uniformity is now sufficient that very thin layers of oxide or nitride may be grown on a silicon wafer in a few seconds.
As silicon integrated circuits are made smaller and smaller, the requirements for the gate dielectrics in MOS field effect transistors grow more stringent. With smaller linewidths, higher speeds and lower power supply voltages; the dielectric in the gate must be made ever thinner. The traditional dielectric material, silicon dioxide (SiO.sub.2) is no longer adequate. The electrical leakage is too high for SiO.sub.2 dielectrics much below 4 nm in physical thickness. The silicon dioxide also does not prevent boron from diffusing from the heavily doped polysilicon gate electrode through the dielectric and into the channel region of the device. This causes a shift of the flatband voltage and oxide quality that severely degrades device performance. For these and other reasons, dielectrics with higher dielectric constants ("high-k dielectrics") and dielectrics which contain species which prevent Boron penetration have been desired. With a higher dielectric constant coefficient, the physical thickness of the layer can be increased for a given equivalent electrical thickness (measured by capacitance). This makes processing easier, provides more resistance to boron penetration and improves other electrical properties such as leakage.
One approach to forming higher k layers and Boron penetration resistant layers has been to add nitrogen to the silicon dioxide film, also called a nitrided oxide. Many processes have been described to form a nitrided oxide including annealing the oxide layer in ammonia, growing the film in nitrous oxide (N.sub.2 O) rather than oxygen, annealing an oxide in nitric oxide (NO), etc. All of these techniques have been shown to have various disadvantages including the location of the nitrogen within the film, high thermal budgets and lack of control and repeatability. In particular, nitrogen is found at the interface between the silicon and the silicon dioxide dielectric, which causes a shift in the flat band voltage. The present invention is a film and a process of making the film to form a nitride/oxide stack layer with desirable properties that overcomes the difficulties of prior methods.